Retatrutide is an experimental weekly injectable medication for obesity and type 2 diabetes, activating three hormone signals for appetite, blood sugar and fat use. In company-funded trials in obesity or diabetes, it produced large weight loss, mostly fat, and better blood sugar, blood pressure, cholesterol and liver fat; whether it prevents heart attacks is not yet known. Nausea is common. It is untested in lean adults and unapproved. (Full Review)

Protocol

Trial regimen (standard)

Subcutaneous injection once weekly

Starting at 2 mg, increasing every 4 weeks via 4, 6 and 9 mg to a maintenance dose of 4, 9 or 12 mg

Time of day

Same weekday each week

Any time of day, with or without food; evening dosing may let early nausea pass during sleep

Lifestyle-first alternative

Structured diet and exercise

The comparator in all trials; for adults without obesity, the evidence-based option, with retatrutide studied only as an add-on

Time to effect

Weight loss

First weeks

Continues for 80 weeks or more

Appetite

Within days

Falls ahead of weight loss

Liver fat

By 24 weeks

Falls substantially

Benefits

High: Body weight and fat mass reduction, glycemic control, blood pressure reduction, blood lipid improvement

Medium: Liver fat reduction, obstructive sleep apnea improvement, knee osteoarthritis pain relief, kidney marker improvement

Low: Fewer cardiovascular events

Speculative: Lower systemic inflammation, slower biological aging, reduced obesity-associated cancer growth

Contraindications

Personal or family history of medullary thyroid carcinoma or MEN2

Pregnancy, attempted conception or breastfeeding

Type 1 diabetes

History of pancreatitis

BMI below 23 kg/m² or underweight (BMI <18.5 kg/m²)

Current or past eating disorder (anorexia nervosa)

Severe gastroparesis

Under 18 years

Key Interactions

Theoretical (inferred from mechanism)

Insulin and sulfonylureas (glipizide)

Other GLP-1–based drugs (semaglutide, tirzepatide)

Blood pressure drugs (lisinopril) and diuretics (hydrochlorothiazide)

SGLT2 inhibitors (empagliflozin)

Oral drugs needing steady absorption (warfarin, oral contraceptives)

Beta-blockers (metoprolol)

NSAIDs (ibuprofen)

Acetaminophen (paracetamol) and other oral over-the-counter drugs

Glucose-lowering supplements (berberine)

Blood-pressure-lowering supplements (potassium)

Fiber supplements (psyllium)

Alcohol

Anesthesia and procedural sedation

Very-low-calorie diets and prolonged fasting

Risk & Side Effects

High: Gastrointestinal adverse events, dysesthesia

Medium: Increased resting heart rate, hypotension, urinary tract infections, hypersensitivity reactions

Low: Lean mass and function loss, gallbladder disease, acute pancreatitis, harms from unregulated products

Speculative: Thyroid C-cell tumors

Monitoring

Marker	Target	Why
Body weight and waist circumference	No established target; track change from own baseline	Primary effect
DXA lean and fat mass	No established target; track change from own baseline	Safety check: lean mass loss
HbA1c	4.0–5.6%	Glucose control
Fasting glucose	70–99 mg/dL	Safety check: hypoglycemia on diabetes drugs
Resting heart rate	60–100 beats per minute	Safety check: heart-rate rise
Blood pressure	<120/<80 mmHg	Safety check: hypotension; expected to fall
Lipid panel (triglycerides, LDL)	Triglycerides <150 mg/dL; LDL: no established target, track change from own baseline	Lipids fall
Serum creatinine with eGFR	Creatinine 0.6–1.3 mg/dL	Safety check: dehydration-related kidney injury
Urine albumin-to-creatinine ratio	<30 mg/g	Albuminuria falls
ALT	7–56 U/L	Safety check: liver injury
Lipase	0–160 U/L, lab-specific	Safety check: pancreatitis

Cadence: Baseline before starting; weekly home weight, heart rate and blood pressure during the escalation phase (first 16–20 weeks); blood tests at 12 weeks and then every 6 months; DXA at 6 and 12 months, then yearly; lipase again only if abdominal pain occurs

Qualitative Assessment

Appetite and satiety control, including fewer food cravings
Energy levels and exercise performance
Strength on key lifts and grip strength
Sleep quality and daytime alertness
Gastrointestinal comfort and bowel regularity
Skin sensations (burning or tingling suggests dysesthesia)
Mood and relationship with food

Retatrutide for Health & Longevity

Protocol

Benefits

Risk & Side Effects

Monitoring

Qualitative Assessment